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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Mon, 11 Sep 2017 00:30:46 +0200
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Subject: Re: Timing issue (?) with wg-quick up on Raspberry Pi B+
To: Jim Darby <uberscubajim@gmail.com>
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Another "direct" debugging thing you could do is:

$ ip link add nlmon0 type nlmon
$ ip link set nlmon0 set up

And then start looking at the output in Wireshark. When you see the
obvious culprit (a rtnetlink message deleting the address), look at
the port ID. Then look in /proc/net/netlink to correlate the port id
("Pid") with an inode ("Inode"). Then look at the symbolic link
targets of /proc/{pid}/fd/[0-9]+ to see which pid has a fd belonging
to that inode. Then we'll know for certain.